A widely used type of lead making machine, referred to as an in-line machine, comprises a wire feeding means for feeding wire along a horizontal straight feed path which extends through upstream (relative to the direction of wire feed) and downstream transfer mechanisms and through wire severing blades and insulation cutting blades which are located between the upstream and downstream wire transferring mechanisms. Crimping presses are located adjacent to the wire severing and insulation cutting blades on one side or on both sides of the feed path. In use, the wire is fed through the transferring mechanisms until the desired length for the lead extends from the severing blades beyond the downstream transferring mechanism. The wire severing and insulation cutting blades are then closed and the transferring mechanisms are moved axially away from the blades to strip insulation from the cut ends of the wire, which extends from the wire source, and the trailing end of the lead which extends through the downstream transferring mechanism. The transferring mechanisms are then shifted to present the stripped ends of the wire and lead to the crimping presses at which terminals are crimped onto the stripped ends. The transferring mechanisms are then returned to their aligned positions on the feed path. A completed lead is removed from the downstream transferring mechanism while the wire from the endless source extends from the upstream mechanism and has a terminal crimped onto its end. The process of feeding the wire, closing the cutting and severing blades, etc., is then repeated to produce the next lead in the series.
Machines of the general type described above are widely used and many different specific types are available. U.S. Pat. Nos. 2,954,599 and 3,030,694 show early versions of machines of this type. One type of machine which is still widely used is shown in U.S. Pat. No. 3,019,679 and a modern machine is described in U.S. Pat. No. 4,554,725. The foregoing U.S. Patents are incorporated into this description by reference. The invention which is described herein can be used on the machines shown in the above-identified U.S. Patents or it can be used on a type of machine which is briefly described below.
On some occasions, problems have been encountered in the wire feeding step in machines of the type described above as a result of the requirement that the leading end of the wire which extends from the source through the upstream transferring mechanism must be fed through the open wire severing and insulation cutting blades at the beginning of the operating cycle. This leading end of the wire will ordinarily have a terminal crimped thereon and additionally, wire sometimes has a memory retained from its being coiled on a spool or the like which causes it to assume a curvature at its end. On some occasions, it has been found that the terminal on the leading end of the wire may encounter one of the severing blades or one of the insulation cutting blades, even though these blades are spaced apart during the feeding cycle. If this happens, the machine must be stopped and corrective action taken. The possibility of misfeeding under such circumstances requires that lead making machines be designed in a manner which will minimize such misfeeds. In accordance with one aspect thereof, the present invention is directed to the achievement of an improved feeding system which completely avoids any possibility of misfeeding as a result of the wire moving against one of the wire severing or insulation cutting blades during feeding.
In-line lead making machines are capable of being operated at relatively high speeds, speeds of 60 cycles per minute being quite common, in which case a finished electrical lead having a terminal on each end is manufactured every second. During the one second cycle time, the wire must be fed, cut, stripped of the insulation on the leading end of the wire and the trailing end of the lead, shifted to the crimping press, and after a terminal has been crimped onto the ends, shifted back in preparation for the next cycle. It follows that only a brief interval, about 0.4 seconds or less, is available for feeding wire during each operating cycle if the cycle period is one second. Wire feeding rolls which rotate at relatively high speeds and are capable of feeding wire at relatively high rates have been developed for in-line lead making machines in order to permit manufacture of long leads when required. However, there are circumstances where it is necessary to reduce the speed of the entire machine for the reason that the wire required for the relatively long leads being manufactured cannot be fed during the feeding interval if the machine is operated at a high speed.
In accordance with a further aspect thereof, the invention is directed to the achievement of a wire feeding system which effectively increases the feeding interval which is available for feeding wire during each operating cycle of an in-line lead making machine. The lengthening of the feeding interval in turn results in an ability to produce longer leads and/or permits operation of the machine at a higher speed (i.e., greater number of cycles per hour) than would otherwise be practical.